1. Field of the Invention
The invention relates to a process for the production of metal foam elements in which a metal powder is mixed with a gas-producing foaming agent powder. More specifically, where the powder mixture is brought to an elevated temperature in a vessel and is extruded through a die, the extruded part being subsequently foamed by heating with decomposition of the foaming agent powder, and then is cooled to produce a finished foam element.
2. Description of Related Art
A process of the initially-mentioned type is known from U.S. Pat. No. 3,087,807. In this known process, a preferably pre-compacted mixture of a metallic powder (preferably aluminum powder) and a gas-producing foaming agent powder (preferably zirconium hydride or calcium carbonate) is poured batchwise, i.e., in a measured amount, into a cylindrical cavity and extruded therefrom through the opening of a die by a ram. The material to be extruded contained in the cavity is, in this case, brought to a temperature suitable for extrusion by resistance heating or induction heating.
Disadvantages of this known process are that the length of the extrudate is limited and that even in the preparation of the amount of powder to be extruded, the latter has to be measured corresponding to the desired length of the extrudate. In this connection, the capacity of the cylindrical cavity sets an upper limit on the size of the product that can be produced and permits only relatively short extruded parts to be obtained, especially if it is desired to dispense with precompacting of the powder.